ASTM 909 Standard Test Method for Supercharge Rating of Spark-Ignition Aviation Gasoline
9. Sampling
9.1 Collect samples in accordance with Practice D4057.

9.2 Protection from Light - Collect and store sample fuels in an opaque container, such as a dark brown glass bottle, metal can, or a minimally reactive plastic container to minimize exposure to UV emissions from sources such as sunlight or fluorescent lamps.

10. Basic Engine and Instrumentation Settings and Standard Operating Conditions
10.1 Installation of Engine Equipment and Instrumentation - Installation of the engine and instrumentation requires placement of the engine on a suitable foundation and hook-up of all utilities. Engineering and technical support for this function is required, and the user shall be responsible to comply with all local and national codes and installation requirements.
10.1.1 Proper operation of the CFR engine requires assembly of a number of engine components and adjustment of a series of engine variables to prescribed specifications. Some of these settings are established by component specifications, others are established at the time of engine assembly or after overhaul, and still others are engine running conditions that must be observed or determined by the operator during the testing process.

10.2 Conditions Based on Component Specifications:
10.2.1 Engine Speed, 1800 r/min +/- 45 r/min, under both firing and non-firing conditions. The maximum variation throughout a test shall not exceed 45 r/min, exclusive of friction measurement.

10.2.2 Compression Ratio, 7.0 to 1, fixed by adjustment of the clearance volume to 108 mL +/- 0.5 mL on cylinders of standard bore by the bench tilt procedure.

10.2.3 Indexing Flywheel to TDC - With the piston at the highest point of travel in the cylinder, set the flywheel pointer mark in alignment with the 0° mark on the flywheel in accordance with the instructions of the manufacturer.

10.2.4 Valve Timing - The engine uses a four-stroke cycle with two crankshaft revolutions for each complete combustion cycle. The two critical valve events are those that occur near TDC; intake valve opening and exhaust valve closing.
10.2.4.1 Intake valve opening shall occur at 15.0° +/- 2.5° BTDC with closing at 50° ABDC on one revolution of the crankshaft and flywheel.

10.2.4.2 Exhaust valve opening shall occur 50° BBDC on the second revolution of the crankshaft and flywheel, with closing at 15.0° +/- 2.5° ATDC on the next revolution of the crankshaft and flywheel.

10.2.5 Valve Lift - Intake and exhaust cam lobe contours, while different in shape, shall have a contour rise of 8.00 mm to 8.25 mm (0.315 in. to 0.325 in.) from the base circle to the top of the lobe.

10.3 Assembly Settings and Operating Conditions:
10.3.1 Spark Advance, constant, 45°.

10.3.2 Spark-Plug Gap, 0.51 mm +/- 0.13 mm (0.020 in. +/- 0.003 in.).

10.3.3 Ignition Settings:
10.3.3.1 Breakerless ignition system basic setting for transducer to rotor (vane) gap is 0.08 mm to 0.13 mm (0.003 in. to 0.005 in.).

10.3.4 Valve Clearances, 0.20 mm +/- 0.03 mm (0.008 in. +/- 0.001 in.) for the intake, 0.25 mm +/- 0.03 mm (0.010 in. +/- 0.001 in.) for the exhaust, measured with the engine hot and running at equilibrium under standard operating conditions on a reference fuel of 100 octane number at the fuel-air ratio for maximum power and an absolute manifold pressure of 101.6 kPa (30 in. Hg).

10.3.5 Oil Pressure, 0.41 MPa +/- 0.03 MPa (60 psi +/- 5 psi) gage in the oil gallery leading to the crankshaft bearings.

10.3.6 Oil Temperature, 74 °C +/- 3 °C (165 °F +/- 5 °F) at the entrance to the oil gallery.
10.3.6.1 Engine Crankcase Lubricating Oil Level:
(1) Engine Stopped and Cold - Oil added to the crankcase so that the level is near the top of the sight glass will typically provide the controlling engine running and hot operating level.
(2) Engine Running and Hot - Oil level shall be approximately mid-position in the crankcase oil sight glass.

10.3.7 Coolant Temperature, 191 °C +/- 3 °C (375 °F +/- 5 °F) in the top of the coolant return line from the condenser to the cylinder.

10.3.8 Fuel Pump Pressure, 0.10 MPa +/- 0.01 MPa (15 psi +/- 2 psi) in the gallery.

10.3.9 Fuel Injector Opening Pressure, 8.2 MPa +/- 0.69 MPa (1200 psi +/- 100 psi) for Bosch nozzle; 9.9 MPa +/- 0.34 MPa (1450 psi +/- 50 psi) for Ex-Cell-O nozzle.

10.3.10 Fuel Injector Timing - The pump plunger must close the fuel-inlet port at 50° +/- 5° ATDC on the intake stroke.

10.3.11 Air Pressure, 0.37 MPa +/- 0.003 MPa (54.4 psi +/- 0.5 psi) absolute at the upstream flange tap of the air flow meter.

10.3.12 Air Temperatures, 52 °C +/- 3 °C (125 °F +/- 5 °F) in the downstream leg of the air-flow meter and 107 °C +/- 3 °C (225 °F +/- 5 °F) in the intake manifold surge tank.

10.3.13 Intake Air Humidity, 0.00997 kg of water/kg (max) (70 grains of water/lb) of dry air.

10.3.14 StandardKnock Intensity, light knock as determined by ear. In determining the light knock point, it is advisable to adjust first to a fairly heavy knock by varying either the manifold pressure or the fuel flow, return to knock-free operation, and finally adjust to the light-knock conditions. Light knock intensity is a level definitely above the commonly defined least audible "trace knock"; it is the least knock that the operator can definitely and repeatedly recognize by ear.

10.3.15 Satisfactory Engine Condition - The engine should cease firing instantly when the ignition is turned off. If it does not, operating conditions are unsatisfactory. Examine the engine for defects, particularly for combustion chamber and spark plug deposits, and remedy such conditions before rating fuels.

10.3.16 Crankcase Internal Pressure - As measured by a gage or manometer connected to an opening to the inside of the crankcase through a snubber orifice to minimize pulsations, the pressure shall be less than zero (a vacuum) and is typically from 25 mm to 150 mm (1 in. to 6 in.) of water less than atmospheric pressure. Vacuum shall not exceed 255 mm (10 in.) of water.

10.3.17 Exhaust Back Pressure - As measured by a gage or manometer connected to an opening in the exhaust surge tank or main exhaust stack through a snubber orifice to minimize pulsations, the static pressure should be as low as possible, but shall not create a vacuum nor exceed 255 mm (10 in.) of water differential in excess of atmospheric pressure.

10.3.18 Exhaust and Crankcase Breather System Resonance - The exhaust and crankcase breather piping systems shall have sufficient internal volume and length dimensions such that gas resonance does not result.

10.3.19 Valve Stem Lubrication - Positive pressure lubrication to the rocker arms is provided. Felt washers are used on the valve stems. A valve and rocker arm cover ensures an oil mist around the valves.

10.3.20 Cylinder Jacket Coolant Level:
10.3.20.1 Engine Stopped and Cold - Treated water/coolant added to the cooling condenser-cylinder jacket to a level just observable in the bottom of the condenser sight glass will typically provide the controlling engine running and hot operating level.

10.3.20.2 Engine Running and Hot - Coolant level in the condenser sight glass shall be within +/- 1 cm (+/- 0.4 in.) of the LEVEL HOT mark on the coolant condenser.

10.3.21 Basic Rocker Arm Carrier Adjustment:
10.3.21.1 Basic Rocker Arm Carrier Support Setting - Each rocker arm carrier support shall be threaded into the cylinder so that the distance between the machined surface of the valve tray and the underside of the fork is 19 mm (3/4 in.).

10.3.21.2 Basic Rocker Arm Carrier Setting - With the cylinder positioned so that the distance between the underside of the cylinder and the top of the clamping sleeve is approximately 16 mm (5/8 in.), the rocker arm carrier shall be set horizontal before tightening the bolts that fasten the long carrier support to the clamping sleeve.

10.3.21.3 Basic Rocker Arm Setting - With the engine on TDC on the compression stroke, and the rocker arm carrier set at the basic setting, set the valve adjusting screw to approximately the mid-position in each rocker arm. Then adjust the length of the push rods so that the rocker arms shall be in the horizontal position.

11. Engine Fit-for-Use Qualification
11.1 Before conducting either of the fit-for-use tests, operate the engine on an aviation gasoline or reference fuel blend in compliance with the basic engine and instrumentation settings and standard operating conditions for approximately one hour to bring the unit to temperature equilibrium.

11.2 Fit-for-Use Qualification After Maintenance - After each top overhaul and whenever any maintenance has been performed other than coolant or lubricant fluid level adjustment or spark plug replacement, the engine shall be qualified as fit for use by establishing its power curve.
11.2.1 Test the reference fuel blend of isooctane + 6.0 mL of TEL per U.S. gallon under standard operating conditions at a constant manifold pressure of 135.4 kPa (40 in. Hg) while varying the fuel flow from lean to rich to cover the fuel-air ratio range from approximately 0.07 to approximately 0.10.

11.2.2 Obtain at least five IMEP versus fuel-air ratio data pairs. Plot the data and fit a smooth curve to determine the maximum IMEP.

11.2.3 The engine is fit for use if the maximum IMEP of the power curve is 164 +/- 5 IMEP. (See Fig. A2.1 and Fig. A2.5 for expected power curve) and the observed FMEP is no more than 3.0 psi from the expected value for the manifold pressure (see Fig. A2.3).

11.3 Fit-for-Use Test for Each Sample - The fit-for-use condition of the engine shall be verified with every sample rating by conformance with the following limits:
11.3.1 For every sample rating, the IMEP values determined for the reference fuels at any fuel-air ratio from approximately 0.09 to approximately 0.12 shall be within +/- 5 % of the value shown in the reference fuel framework at that fuel-air ratio.

11.3.2 For every sample rating, at any fuel-air ratio from approximately 0.09 to approximately 0.12, the spread (difference) between the knock-limited power curves for the bracketing reference fuels shall be within +/- 30 % of the spread shown in the reference fuel framework at that fuel-air ratio.

12. Checking Engine Performance
12.1 Checking Performance on Check Fuels:
12.1.1 While engine standardization is dependent solely on power curve compliance, rating check fuels can be done to determine the accuracy (lack of bias) of the engine.
12.1.1.1 Test check fuel(s).

12.1.1.2 Compare the supercharge rating obtained for the check fuel to the check fuel supercharge rating ARV.

12.1.1.3 Specifics for control chart setup and interpretation of the delta between the rating and the ARV value can be found in Practice D6299.

12.1.1.4 If an out-of-statistical control situation is detected, examine the engine system operation for assignable cause(s).

12.2 Quality Control (QC) Testing - Users may conduct a regular statistical quality control program to monitor the engine is in statistical control over time.
12.2.1 This test method suggests validating the engine system by the rating of a QC sample.

12.2.2 The QC sample is a typical spark-ignition aviation fuel having a supercharged rating within the normal operating range of the engine.

12.2.3 Use appropriate control charts or other statistically equivalent techniques to assess the supercharge rating. Control charts often used for this application are Individuals and Moving Range (I/MR).

12.2.4 Specifics for control chart setup and interpretation can be found in Practice D6299.

12.2.5 If an out-of-statistical control situation is detected, examine the engine system operation for assignable cause(s).